Regarding a traditional chain structure power transmission for using a chain is usually transmitted by a drive wheel, the shape of the teeth of which is standardized. A more developed chain structure in this respect is previously known e.g. from Finnish patents FI 64707 and FI 101098. The chains presented in these patents consist of shaped pieces to be coupled with each other one after the other by jointing points thereof, whereby the supporting surfaces of the shaped pieces comprise notches existing crosswise in respect to the moving direction to the chain, the notch in each shaped piece being placed advantageously near one of the jointing points of the shaped piece. In this case, when the chain gets bent over the drive wheel, an advantageous lever arm is achieved, thanks to which the chain force influencing the chain structure presses the notches of the chain harder against the pins of the drive wheel. This solution decreases significantly so called skipping. Also thanks to the level arms being formed, the chain structure gets easily loose from the drive wheel on its return side, thanks to which a so called non-engagement of the chain is prevented.
The chain structure according to Patent FI 64707 has proved to be significantly better than corresponding earlier solutions, particularly thanks to the lever arms being achieved therewith. In certain purposes, such as in chain structures, being used in water refineries, plastics or corresponding non-metallic materials have been exploited, because e.g. of corrosion and in order to decrease the specific gravity of the chain. In this case, in certain environments, such as e.g. in acid conditions, problems have arisen related to duration of the plastic material of the shaped pieces.
On the other hand, in patent FI 101098 there has been presented an improvement for the part of the bending of a chain particularly along the longitudinal direction of the joint pins, which is minimized by using joint pins, being uniform in the longitudinal direction thereof and the cross section of which increases towards one end thereof. When exploiting furthermore advantageously e.g. joint pins, that are continuously conical, the surface pressures may be optimized under all circumstances in a way, that the type of bending of the chain may be even totally eliminated in principle. In addition to that, by exploiting the type of joint pins even mounting of the chain may be eased by the guiding effect of the conical joint pin.
Improving the tensile strength and the bending stiffness of the shaped pieces have been tried usually by increasing material thickness of the shaped pieces at the point of the notch on the opposite side with respect to the supporting surface, which can not be carried out optimally under all circumstances from the point of view of functionality of the use of chain. This is first of all due to the fact that increasing the distance of the back part of the shaped piece from a center line defined by the joint pins of a chain brings about problems particularly in the guiding of the passage of the chain as well as in the controlling of its passage i.e. in the functioning of e.g. so called chain guides. On the other hand, it is more profitable to arrange the depth of a notch in a shaped piece to extend in the shaped piece essentially at the center line of the chain, which enables an optimal power transmission between the drive wheel driving the chain and the shaped pieces of the chain. In this way it is made possible carrying out of the chain in an optimized manner both structurally and regarding its functioning without extra swing and vibration. With chains that are put together with shaped pieces, being in use at present, the problems described above can not be satisfactorily solved.